Rolling apparatus



Feb. 8, 1955 w, BEDKER 2,701,484

ROLLING APPARATUS Filed April 50, 1952 2 Sheets-Sheet l L l lllllqlhillm m g 3 #1 INVENTOR. MLEO W.BEDKER BY W WYM? ATTO R N EYS Feb. 8, 1955 w. BEDKER 2,701,484

ROLLING APPARATUS Filed April 30, 1952 2 Sheets-Sheet 2 INVENTOR.

LEO W.BEDKER ATT RNEYS ROLLING APPARATUS 7 Leo W. Bedker, East Detroit, Michr Application April 30, 1952, Serial No. 285,193

2 Claims. (Cl. sir-5.1

I The present application relates to rolling apparatus and is a continuation-in-part of my prior copending application Serial No. 189,244 filed October 9, 1950, now abanone It is an object of the present invention to provide in rolling apparatus of the character described, lost motion means between a pair of opposed vrolls to permit differential motion therebetween.

, It is a further object of the present invention to provide a pair of opposed rolls, gears interconnecting the rolls for simultaneous rotation, lost motion means included in the driving connection between the rolls, and support means to provide for initial contact between one of the rolls anda work piece in advance of engagement between the other roll and the work piece.

Other objects and features of the invention will becomeapparent as the description proceeds, especiallywhen.

taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a side elevation, with parts in section, of a holder showing its attachment to a slide for moving the holder.

Figure 2 is an elevational view of the structure shown in Figure 1, as seen from below and to the right.

Figure 3 is an exploded perspective view illustrating a preferred form of lost motion driving connection between a roll and a drive gear coaxial therewith.

Figure 4 is a side elevational view with parts in sectign, showing the holder as supported from the opposite si e. v

Figure 5 is an elevational view of the structure shown in Figure 4, as seen from below. and to the right.

Figure 6 is an elevational view of the structure shown in Figure 4, as seen from below and to the left. 1

Figure 7 is a diagrammatic view illustrating the relation'ship between'the pair of opposed rolls and the work piece at initial contact and at final depth. I

v.The present invention relates generally to the art of rolling and moreparticularly, to the art of thread rolling. Accordingly, it will be described in conjunction with a thread rolling fixture although work of different types, such for example as knurling, may be accomplished merely by the substitution of knurling rolls for thread ro ls.

The operation for which the present mechanism was devised comprises passing a pair of opposed rolls in straddling relation over a rotating work piece. The rolls are interconnected by a train of gears so that rotation imparted to one roll is transmitted to the other roll. However, the mounting for the rolls and the gearing is designed to permit as free rotation as possible so as to impose no substantial load or resistance to rotation on either of the rolls when in contact with the work piece. It is essential for thread rolling, and of even more critical consideration in knurling, that the rolls be in exactly oriented position at the instant when the secondv of the two rolls comes into engagement with'the work piece. This is necessary in order that the threads or the depressions or knurls shall be in accurate relationship. In the case of knurling it will be appreciated that if the rolls were out of phase by an amount equal to half a pitch of the knurls on the work piece, twice as many knurls would be provided on the work piece as intended. In the same way it is necessary for a thread groove initiated by one roll to track properly with the, projections on the opposite thread roll. The spacing between the thread rolls is necessarily such that the thread rolls contact the work United States Patent 0 pieceat points less than 180 degrees apart.

H knurls, it will be apparent that each knurling roll will After this initial contact has taken place further feed of the rolls in a direction perpendicular to the axis of the work piece is required until the rolls reach or slightly pass the centerline of the work piece. This additional feed after the rolls have come into contact with the work piecerequires differential rotation between the rolls. .This differential rotation is provided by lost motion in the gearingconnecting the rolls. I i

The rolls may be thread rolls .or they may be rolls with their surfaces suitably shaped to provide a knurled surface on the Work piece. The problem overcome by the present invention is particularly present in the case of rolling knurled surfaces in which a series of axially extending" It will be ap grooves are provided in the work piece. preciated that in order to obtain satisfactory results, the two knurling rolls must be in accurately oriented posie tions of rotation such that the raised ribs on'bo'th of :the

rolls track properly or mesh with the depressions formed in the knurled surface of the work piece. When the two rolls are incenter position on a completed work piece the three parts should roll together in the manner of spur gears. angular relationship with respect to the other by anamount equal to half the circumferential pitch of the form its own knurled recesses on the work piece and consequently the work piece would have twice as many recesses as desired. Moreover, the operation would not.

be satisfactory since the parts are designed so that each knurled recess is progressively formed as the knurling I rolls are advanced to center position on the work piece and the action of both rolls is required to properly form each of the knurled recesses on the work piece.

The same problem ispresent in a less aggravated degree when rolling threads. It will be readily apparent that if a series of circumferential grooves, rather than a continuoushelical thread is to be rolled on the work piece, the angular position of the rolls would be of no. However, when the thread to be rolled ex-,

significance. tends at a helix angle, misalignment between the rolls results in axial shifting of the threads by an amount which is a function of the helix angle of the thread. It has been found that where the lost motion device disclosed herein is not employed, satisfactory thread rolling may be accomplished but it results in undesirable stresses on the thread rollswith the result that thread roll life is appreciably shortened.

The foregoing is illustrated in Figure 7 of the drawings wherein the opposed rolls 26 and 28 are illustrated in full line condition at the instant when both of said" rolls are in contact with the work piece W. The rolls are shown in dotted line position after they have'rolled the work piece to full depth, at which time they are at,

in a clockwise direction as seen in this figure and as indi-. cated by the dotted line arrow applied to the roll 26, whereas the lower thread roll would rotate in a counterclockwise direction as indicated by the dotted line arrow applied thereto. With the thread rolls in the full line position and without traverse to the right as seen in this figure, it willbe appreciated that rotation of the work piece, as for example in a clockwise direction as indicated by the full line arrowapplied thereto, will result in counterclockwise rotation of the thread roll 26, as indicated by the full line arrow applied thereto, and will result in counterclockwise rotation of the thread roll 28 as indi- It will fur' cated by the full line arrow applied thereto. ther be observed that the rotation attributable to traverse of the roll 26, and as indicated by the dotted line arrow,

is in a direction opposite to the rotation thereof attributable to rotation of the work piece W and indicated by the full line arrow, so that the resultant rotation of the thread roll 26 is therefore equal to the value of the rotation indicated by the full line arrow less the valued the rotation indicated by the dotted line arrow. Qn thef If one of the rolls happens to be out of proper,

contrary, the rotation of the thread roll 28 attributable to traverse and indicated by the dotted line arrow, is in the same direction as the rotation of the thread roll 28 attributable to the work. piece and indicated by the full line arrow, so that the resultant rotation of the thread roll 28 is equal to the value of the rotation indicated by the full line arrow plus the value of the rotation indicated by the dotted. line arrow. It is therefore apparent that thethread rolls 26 and 28will have unequal or diiierential rotation during advance onto the Work piece.

t The holder for the rolls is supported on a slide inovable in a plane perpendicular to the axis of the work piece and is definitely located thereon in a position such that a predetermined one of the rolls will contact the work piece in advance of the other roll so as to permit the lost motion in the gearing to be positively taken up in the proper direction before contact. between the secondv roll and the work piece. At the same time, the holder is resiliently supported so that during the time between. contact of the first roll and the work piece, and contact of the second roll and the work piece, the holder is displaced against a spring so as to center the holder properly with respect to the work piece.

With the foregoing general description in mind, in Figure 1 there is illustrated a holder having a shank 12 provided with an opening 14 which receives a pivot pin 16 extending between spaced cars 18 of an adaptor 20 secured to a machine slide 22. In practice the slide 22 may be one of the slides provided on an automatic screw machine.

The holder 10 includes a bifurcated head 24 adapted to support a pair of rolls 26 and 28, the spacing between the rolls being adjustable as a result of the provision of an elongated slot 30 which receives the spindle of one of the rolls. The rolls 26 and 28 are operatively connected to gears 32 and 34 respectively, and the gears 32 and 34 are connected by a train comprising the gears 36, 38 and 40.

Lost motion in the gear train is provided in any suitable. way. Thus for example, as illustrated in Figure 3, one of the rolls 26 may be connected to its associated gear 32 by means of a relatively narrow driving key 42 on the gear which operates in a relatively wide slot 44 provided at the end of the roll 26 between lugs 46 and 48.

In order to position the holder 10 in a position such that the roll 26 will engage the work piece W' in advance of engagement between the roll 28 and the work piece, the holder is provided with a transverse openingv therethrough indicated at 50, which receives a screw 52, the upper end of which is threaded into a recessin the adaptor 20'. Adjacent the upper side of the holder Ill, the opening 50 is laterally enlarged as indicated at 54 and a coil compression spring 56 is received in the lateral. enlargement surrounding the screw 52. This spring biases the holder in a counterclockwise direction about the axis of the pin 16 and the exact location of the holder is determined by the position of a nut 58 which in turn is retained in position by a lock nut 60.

The slide 22 is reciprocable in the direction of the arrow 62 andadvance of the slide moves the holder 10 forwardly until the roll 26 contacts the rotating periphery of the driven workv piece: W, which is shown in Figure 2 as driven by a chuck C. Inasmuch as the thread rolls and the gearing interconnecting the rolls. are designed for particularly free rotation, the roll 26 immediately is driven in rotation by the work piece and this rotation is transmitted through the gearing. to the roll 28. The position of the holder 10 at the instance of contact of the holder 10 and. the. work piece is such that further advance of the slide causes a slight clockwise rotation of the holder until the roll 28 engages the work piece. The adjustment of the initial position of the holder is such that contact between the roll 26 and the work piece precedes contact between the. roll 28 and the work piece by an. amount sufiicient to insure that all lost motion has. been taken out of the transmission between the rolls. Thus, when the roll 28 initially contacts the work piece. it is in precisely correct oriented position with respect to the roll 26.. During further advance of the. slide 22 differential rotation isperm-itted between the rolls, each roll being driven independenty by its contact with the rotating work rece.v P The thread rolling operation comprises a relatively rapidadvance and retraction of the holder with the roll in straddling relation to the work piece to a posltion 1n which the rolls are at or slightly beyond the center-line of the work piece.

After retraction of the holder the rolls may or may not be in properly oriented position but if they are not properly oriented they become oriented as previously described during the succeeding operation.

In Figures 4-6 there is illustrated an arrangement in which the holder 10 is supported at the opposite side of an automaticscrew machine. In this case the roll 26 is again to contact the rotating work piece in advance of the roll 28. 'With thismounting however, it is necessary to provide a different structure for supporting and adjusting the holder 10-. In this case a compression spring is provided having one end limited in the enlargement 54 of the holder and the other end engaging adjustable nuts 72 so that the compression of the spring may be varied. The spring is selected to have such strength to support the weightof theholder and the initial position of the holder is determined by an adjustable abutment screw 74 provided with a lock nut 76 and having a portion 78 extending through thehol'der and engaging the bottom wall 80 of the slot in the adaptor 22. In this case the operation is precisely the same as in the. previously described setting of the holder. The adaptor 22. is rigid- 1y secured to a slide 82 Which is movable in a plane perpendicular to the axis of the rotating work piece. The direction of traverse of the slide in. this case is indicated by the arrow 84. Initial contact between the roll 26- and the work piece results in rotation of the roll 26 and the taking up of all lost motion in the gear train between the rolls 26 and 28. Since the initial location of the holder is not centered with respect to the work piece, further advance of the slide causes the holder 10 to rock in a clockwise direction a slight amountagainst the .opposition of the spring 70 until such time as the roll 28 engages the work piece. Since the lost motion in the gearing, will have been taken up before contact of the roll 28 and the work piece, the rolls 26 and 28 will be in precisely oriented position at the instant of contact between the roll 28 and the work piece. Further ad'- vance of the holder to cause the rolls to reach or slightly pass the center-line of the work piece will result in a diiferential rotation between the rolls, each roll being. driven independently by the rotating work piece.

Attention is directed to the fact that it is essential for successful operation of the rolls for the rolls to be driven by the work piece without appreciable resistance to turning. This is accomplished in the present instance'by providing a gear train characterized by its freedom of action. in conjunction with the lost motion mechanism therein. With the freely rotatable parts thus provided, the present invention provides mechanism whereby the lost motion will be taken up just prior to the critical instant when the second of the two rolls engages the work piece so that at this instance the two rolls are in properly oriented relationship to each other. As soon as the second roll engages the work piece, which takes place during continuous advance of the holder 10, this roll is driven in rotation by the work piece. It will be observed that at the instant when. the second roll engages the work piece, it will be rotating at substantially the proper speed to roll therewith. The slight variation in speed necessary to provide for free rolling of the roll during continned advance of the holder is thus quickly imparted thereto. On the other hand, it will be apparent that when the first roll contacts the work piece, both rolls and the train of gears is stationary so that some small slippage may result between the surface of the work piece and the first roll. This is unimportant however since by the adjustment of the holder sufiicient time allowed to permit the first roll to pick up its full speed as a result of the spring, pressure biasing the holder in a direction to cause the first roll to bear against the work piece. This permits the first roll to cause the gear train to take up its lost motion and to drive the second roll through this gearing.

One of the important features of the present invention is the arrangement by which the holder may be accurately adjusted as to initial position so as to predetermine the interval between contact of the first roll'with the work piece and contact of the second roll with the work piece. A second important feature of the present invention is. in the provision of resilient means. which predetermines thepressure contact between the. first roll to contact the work piece and the work piece during the interval between this contact and the contact between the second roll and the work piece.

The drawings and the foregoing specification constitute a description of the improved rolling apparatus in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

1. In a machine having a rotary driving work support and a tool slide movable rectilinearly toward and away from the work support in a plane perpendicular to the axis of the work support, the improvement which comprises a holder, pivot mounting means on said slide for supporting said holder for angular movement about a pivot axis parallel to the axis of said Work support and located such that said pivot axis moves substantially radially toward and away from the axis of the work support upon rectilinear movement of the slide, means in said holder spaced from the pivot axis thereof for mounting a pair of forming rolls spaced apart to straddle a work piece carried by said work support and with their axes substantially parallel to the axis of said work support and located approximately in a plane perpendicular to the common plane of the axes of said work support and pivot mounting means, an abutment carried by the slide and engageable by said holder to locate said holder in an angular position such that said rolls advance toward the axis of said work support with the axis of a first one of said rolls in a plane closer to said common plane than the plane of advance of the axis of the second one of said rolls so that said first roll contacts a rotating work piece in said work support substantially in advance of said second roll, resilient means operatively connected to said holder to retain said holder in engagement with said abutment during advance of said slide toward said work support, said resilient means being yieldable to provide for angular movement of said holder after said first roll engages the work piece to center said rolls with respect to the work piece upon continued forward movement of the slide, and gearing including lost motion means interconnecting the means for mounting said rolls to insure proper angular relationship between said rolls and to insure equal peripheral speeds of said second roll and work piece at the instant of contact between said second roll and the work piece, the lost motion means providing for the required differential rotation between said rolls as they are driven at difierent speeds by the work piece during further advance of said holder.

2. In a machine having a rotary driving work support and a tool slide movable rectilinearly toward and away from the work support in a plane perpendicular to the axis of the work support, the improvement which comprises a holder, said holder comprising means for supporting a pair of forming rolls thereon with their axes spaced apart to straddle a work piece carried by the work support and with their axes substantially parallel to the axis of said work support and located approximately in a plane perpendicular to a reference plane passing through the axis of the work support and parallel to the path of advance of said tool slide, mounting means on said slide for supporting said holder for movement relative thereto efiective to move the means for mounting said rolls in a direction substantially perpendicular to said reference plane and substantially perpendicular to the axis of said work support, an abutment carried by said slide and engageable by said holder to locate said holder in a position such that said rolls advance toward the axis of said work support with the axis of a first one of said rolls in a plane closer to said reference plane than the plane of advance of this axis of the second one of said rolls so that said first roll contacts a rotating work piece in said work support substantially in advance of said second roll, yieldable means operatively connected to said holder to retain said holder in engagement with said abutment during advance of said slide toward said support but yieldable to provide for movement of said holder after said first roll engages the work piece sufiicient to center said rolls with respect to the work piece upon continued forward movement of the slide, and gearing including lost motion means interconnecting the means for mounting said rolls to insure proper angular relationship in rotation between said rolls and to insure equal peripheral speeds of the second roll and work piece at the instance of contact between said second roll and the work piece, the lost motion means providing for the required differential rotation between said rolls as they are driven at different speeds by the work piece during further advance of said holder.

References Cited in the file of this patent UNITED STATES PATENTS 1,145,661 Bailey July 6, 1915 1,731,314 Mohr Oct. 13, 1929 2,355,132 Aflleck Aug. 8, 1944 2,421,667 Veit June 3, 1947 2,645,953 Schlitters July 21, 1953 FOREIGN PATENTS 480,973 Canada Feb. 12, 1952 

